A conventional hand tool generally does not include a strain transducer which is able to measure and indicate the torque that the workpiece is applied by the hand tool. U.S. Pat. No. 4,006,629 discloses a torque measuring apparatus which includes four strain transducers on two sides of the handle, and a display member is located on the handle so as to display the torque that the four strain transducers measure. A conductive wire extends from the display member and might be pulled unintentionally or be tangled by objects around the hand tool to cut off the circuit. Besides, four strain transducers are so costly that the hand tools are not competitive in the market.
The present invention intends to provide a hand tool that includes a hole defined through the handle and a strain transducer is installed close to the hole. The section with the hole of the handle is deformed so that the strain transducer can easily measure the torque.